Plasma addressing structures may be employed in a variety of applications including data storage devices, video cameras, and flat panel liquid crystal displays. One such addressing structure is described in U.S. Pat. No. 4,896,149 of Buzak et al. for "Addressing Structure Using Ionizable Gaseous Medium".
A preferred embodiment of this addressing structure includes an ionizable gas captured within each of multiple channels that are separated by elongated support structures, which extend in one direction across a display screen with the channels. The support structures provide complete isolation of the gas in each of the channels. The gas in each channel is selectively ionized to address a row of display elements aligned with the channel. The gas is ionized by a gas ionizing structure that includes an electrical reference electrode or anode and a data strobe electrode or cathode that extend along the length of each channel.
While the gas in a channel is ionized, data signals are delivered to the addressed display elements on multiple data electrodes extending across the display screen in a direction perpendicular to the direction in which the channels extend. A liquid crystal material positioned between the channel arrangement and the data electrodes is responsive to the data signals to form a display image.
FIG. 1A is an elevated fragmentary view of a prior art glass substrate 10 within which multiple parallel channels 12 are inscribed or etched for containing an ionizable gas. Adjacent channels 12 are separated by sidewalls 20 that define multiple elongated support structures 22 with top surfaces 16 that support various addressing structure components including an appropriate dielectric sheet and a liquid crystal material (not shown).
A strobed row electrode or cathode 30 and a grounded reference electrode or anode 32 are positioned on an inner surface 34 of each channel 12. Cathodes 30 and anodes 32 are relatively thin, narrow metal coatings. Each of cathodes 30 receives a row strobe signal from a corresponding output amplifier 36 of a data strobe circuit 38 for selectively ionizing a gas contained within the channel 12.
FIG. 1B is a cross-sectional view of substrate 10 showing that support structures 22 have relatively broad bases 42 and relatively narrow top surfaces 16. The widths 44 and 46 of respective channels 12 and bases 42 are substantially greater than the widths 48 of top surfaces 16. As a consequence, top surfaces 16 represent only a small proportion of the surface area of substrate 10, thereby providing correspondingly little support for dielectric sheet 24, the liquid crystal material, and the other components positioned over and supported by substrate 10.
The relatively little surface area provided by top surfaces 16 to support dielectric sheet 24 and other components allows then to be excessively pliant or flexible. Such pliancy is undesirable because it allows the possibility of fracture of the dielectric sheet and excessive variation in spacing of the liquid crystal.